The present invention relates to the inspection of materials and in particular to the inspection of materials using a penetrant including a vegetable based fatty acid ester.
Fluorescent Penetrant Inspection (FPI) and Visible Penetrant Inspection VPI) are used to increase the visibility of a flaw in a material. FPI and VPI are performed by applying a penetrant solution to an inspection area on the surface of the material. The penetrant solution enters surface openings of the flaw. The inspection area is then wiped or rinsed to remove any penetrant solution residing on the surface of the material and a developer is applied to the inspection area. The developer draws the remaining penetrant material from the flaw opening. Flaws or cracks in the inspection area will then be visible under the influence of ultraviolet light (black light) when using a fluorescent penetrant or white light when using a visible penetrant. FPI and VPI are effective for detecting surface flaws in forgings, castings, extrusions, formed sections, webs, and skins of materials.
Known fluorescent penetrant solutions generally include petroleum distillates. Known visible penetrants used for VPI also include environmentally harmful petroleum distillates. Such petroleum distillates are environmentally harmful and require appropriate handling. Growing societal sensitivity to environmental issues has resulted in a need to find environmentally friendly alternatives.
Known fluorescent penetrant solutions also are sensitive to temperature. If such known fluorescent penetrant solutions are heated very much above ambient, the known fluorescent penetrant solutions breakdown. This sensitivity to temperature prevents heating the penetrant in applications of FPI which would benefit from heating the fluorescent penetrant.